Hi

Im reading a little about security and after i read about what a backdoor and a rootkit was i got a little confused. Could someone please explain the difference between these too ?

I would also really like to know the difference is between a virus and a worm.

Thanks in advance

This really sounds like homework, and is probably easily answered by your textbook.

Backdoor - You built the system, but left a hidden way for you to get in later.
Rootkit - Something illegally installed on someone elses system, which lets them get in.
Virus - Your system is infected, for whatever purpose, with a program that damages something, or lets someone else do something nasty.
Worm - Similar, but propagates in a less 'focused' way, sending out feelers everywhere it can find, from every machine it infects.

I'm sure there are lots of other simple explanations...best to look them up yourself.

Thanks for your answer TB0ne.

Yes it probably looks like home work to you, but its not. I know very well that its always best to look up things yourself, but ive been reading a lot on wikipedia (no, not a textbook and I just wanted to see someone else' explainations of this since I didnt quite get what the difference was.

Taxonomy-wise I'd say a rootkit literally is just a container, the rest are applications with a specific task. A rootkit basically is the toolkit with which one keeps illegal access covert. A rootkit can contain trojaned binaries, LKM's, backdoored binaries, scanners, exploits, daemons, communication tools and whatever else one thinks one needs. Binaries in rootkits can be infected with a virus. Note that viruses (aprox 10 PoCs, one commonly found ITW) aren't the issue on *NIX.